Does the phrase "Your daughter is unlawful to me by three" count as a final, irrevocable divorce (talaq bain) or a single revocable divorce (talaq raj'i)?

A man's statement to his wife, "You are forbidden to me by three" is a euphemism for divorce, and its ruling depends on his intention. If he intended ẓihār (a pre-Islamic form of divorce), then it is ẓihār. If he intended divorce, then it is a divorce. If he intended an oath, then it is an oath. If he did not intend anything, then it is an oath.

What appears from his statement ("by three") is that he intended divorce. In this case, it counts as one pronouncement of divorce, and he has the right to take her back as long as she is within her waiting period ('iddah) and this was not the third pronouncement.